Complementary Phenotyping of Maize Root System Architecture by Root Pulling Force and X-Ray Imaging.

The root system is critical for the survival of nearly all land plants and a key target for improving abiotic stress tolerance, nutrient accumulation, and yield in crop species. Although many methods of root phenotyping exist, within field studies, one of the most popular methods is the extraction and measurement of the upper portion of the root system, known as the root crown, followed by trait quantification based on manual measurements or 2D imaging. However, 2D techniques are inherently limited by the information available from single points of view. Here, we used X-ray computed tomography to generate highly accurate 3D models of maize root crowns and created computational pipelines capable of measuring 71 features from each sample. This approach improves estimates of the genetic contribution to root system architecture and is refined enough to detect various changes in global root system architecture over developmental time as well as more subtle changes in root distributions as a result of environmental differences. We demonstrate that root pulling force, a high-throughput method of root extraction that provides an estimate of root mass, is associated with multiple 3D traits from our pipeline. Our combined methodology can therefore be used to calibrate and interpret root pulling force measurements across a range of experimental contexts or scaled up as a stand-alone approach in large genetic studies of root system architecture.

The state of general surgery training: a different perspective.

BACKGROUND: Much has been written about the influences of Accreditation Council for Graduate Medical Education (ACGME) work restrictions, the litigious climate in American medicine, and the proliferation of subspecialty fellowships on general surgery training. Few previous studies have addressed general surgical residents' perceptions of surgical training on a national level. METHODS: A 38-question Institutional Review Board-approved survey was sent via e-mail to the program directors at all ACGME-approved general surgical training programs for distribution to categorical general surgery residents. Voluntary responses to statements focusing on job satisfaction, quality of life, and the influences of operative experience, work hours, fellows, physician extenders, as well as faculty and administration on resident training were solicited. RESULTS: Overall, 997 responses were received from residents of all clinical levels from 40 states. Most respondents were from university-based programs (79%) with a broad representation of program sizes (mean of 6 graduates per year; range 2 to 11). Residents believe that they will be prepared to enter clinical practice at the conclusion of their training (86%), that the duration of surgical training is adequate (85%), and that they are exposed to sufficient case volume and complexity (85% and 84%, respectively). Only 360 respondents (36%) believe that they are financially compensated appropriately. Although most respondents support the ACGME work-hour restrictions (70%), far fewer feel that they improve their training or patient care (46.6% and 46.8%, respectively). Most respondents are proud to be surgical residents (88%), view surgery as a rewarding profession (87%), and would choose surgery as a profession again (77%). CONCLUSIONS: Surgical residents are positive regarding the quality of their training and life, although they feel poorly compensated for their work. Most residents intend to pursue fellowship training. Survey responses were consistent irrespective of gender, ethnicity, and program type.

Genetic analysis of the gravitropic set-point angle in lateral roots of Arabidopsis.

Research on gravity responses in plants has mostly focused on primary roots and shoots, which typically orient to a vertical orientation. However, the distribution of lateral organs and their characteristically non-vertical growth orientation are critical for the determination of plant form. For example, in Arabidopsis, when lateral roots emerge from the primary root, they grow at a nearly horizontal orientation. As they elongate, the roots slowly curve until they eventually reach a vertical orientation. The regulation of this lateral root orientation is an important component affecting overall root system architecture. We found that this change in orientation is not simply due to the onset of gravitropic competence, as non-vertical lateral roots are capable of both positive and negative gravitropism. Thus, the horizontal growth of new lateral roots appears to be determined by what is called the gravitropic set-point angle (GSA). This developmental control of the GSA of lateral roots in Arabidopsis provides a useful system for investigating the components involved in regulating gravitropic responses. Using this system, we have identified several Arabidopsis mutants that have altered lateral root orientations but maintain normal primary root orientation.

Spatial separation of light perception and growth response in maize root phototropism.

Although the effects of gravity on root growth are well known and interactions between light and gravity have been reported, details of root phototropic responses are less documented. We used high-resolution image analysis to study phototropism in primary roots of Zea mays L. Similar to the location of perception in gravitropism, the perception of light was localized in the root cap. Phototropic curvature away from the light, on the other hand, developed in the central elongation zone, more basal than the site of initiation of gravitropic curvature. The phototropic curvature saturated at approximately 10 micromoles m-2 s-1 blue light with a peak curvature of 29 +/- 4 degrees, in part due to induction of positive gravitropism following displacement of the root tip from vertical during negative phototropism. However, at higher fluence rates, development of phototropic curvature is arrested even if gravitropism is avoided by maintaining the root cap vertically using a rotating feedback system. Thus continuous illumination can cause adaptation in the signalling pathway of the phototropic response in roots.

Kinetics of constant gravitropic stimulus responses in Arabidopsis roots using a feedback system.

The study of gravitropism is hindered by the fact that as a root responds, the gravitational stimulus changes. Using a feedback system to connect a rotating stage platform to a video digitizer system, we were able to maintain a constant angle of gravistimulation to Arabidopsis roots for long time periods. The rate of curvature approximated the sine rule for angles of stimulation between 20 degrees and 120 degrees. For a given angle of stimulation, the rate of curvature also remained constant, with no observed diminishment of the response. Although previous reports of Arabidopsis root gravitropism suggest latent periods of approximately 30 min, using a smooth mechanical stage to reorient the root, we observed a mean time lag of approximately 10 min. This more rapid onset of curvature can, in part, be explained by reduced mechanical perturbation during the process of gravistimulation. This suggests that mechanical stimulation associated with rapid root re-orientation may confound investigations of early gravitropic events.

Two distinct regions of response drive differential growth in Vigna root electrotropism.

Although exogenous electric fields have been reported to influence the orientation of plant root growth, reports of the ultimate direction of differential growth have been contradictory. Using a high-resolution image analysis approach, the kinetics of electrotropic curvature in Vigna mungo L. roots were investigated. It was found that curvature occurred in the same root toward both the anode and cathode. However, these two responses occurred in two different regions of the root, the central elongation zone (CEZ) and distal elongation zone (DEZ), respectively. These oppositely directed responses could be reproduced individually by a localized electric field application to the region of response. This indicates that both are true responses to the electric field, rather than one being a secondary response to an induced gravitropic stimulation. The individual responses differed in the type of differential growth giving rise to curvature. In the CEZ, curvature was driven by inhibition of elongation, whereas curvature in the DEZ was primarily due to stimulation of elongation. This stimulation of elongation is consistent with the growth response of the DEZ to other environmental stimuli.

Inhibition of root elongation in microgravity by an applied electric field.

Roots grown in an applied electric field demonstrate a bidirectional curvature. To further understand the nature of this response and its implications for the regulation of differential growth, we applied an electric field to roots growing in microgravity. We found that growth rates of roots in microgravity were higher than growth rates of ground controls. Immediately upon application of the electric field, root elongation was inhibited. We interpret this result as an indication that, in the absence of a gravity stimulus, the sensitivity of the root to an applied electric stimulus is increased. Further space experiments are required to determine the extent to which this sensitivity is shifted. The implications of this result are discussed in relation to gravitropic signaling and the regulation of differential cell elongation in the root.

Inhibition of root elongation in microgravity by an applied electric field.

Roots grown in an applied electric field demonstrate a bidirectional curvature. To further understand the nature of this response and its implications for the regulation of differential growth, we applied an electric field to roots growing in microgravity. We found that growth rates of roots in microgravity were higher than growth rates of ground controls. Immediately upon application of the electric field, root elongation was inhibited. We interpret this result as an indication that, in the absence of a gravity stimulus, the sensitivity of the root to an applied electric stimulus is increased. Further space experiments are required to determine the extent to which this sensitivity is shifted. The implications of this result are discussed in relation to gravitropic signaling and the regulation of differential cell elongation in the root.

Root-growth behavior of the Arabidopsis mutant rgr1. Roles of gravitropism and circumnutation in the waving/coiling phenomenon.

In this study we investigated the kinetics of the gravitropic response of the Arabidopsis mutant rgr1 (reduced root gravitropism). Although the rate of curvature in rgr1, which is allelic to axr4, was smaller than in the wild type (ecotype Wassilewskija), curvature was initiated in the same region of the root, the distal elongation zone. The time lag for the response was unaffected in the mutant; however, the gravitropic response of rgr1 contained a feature not found in the wild type: when roots growing along the surface of an agar plate were gravistimulated, there was often an upward curvature that initiated in the central elongation zone. Because this response was dependent on the tactile environment of the root, it most likely resulted from the superposition of the waving/coiling phenomenon onto the gravitropic response. We found that the frequency of the waving pattern and circumnutation, a cyclic endogenous pattern of root growth, was the same in rgr1 and in the wild type, so the waving/coiling phenomenon is likely governed by circumnutation patterns. The amplitudes of these oscillations may then be selectively amplified by tactile stimulation to provide a directional preference to the slanting.

Analysis of changes in relative elemental growth rate patterns in the elongation zone of Arabidopsis roots upon gravistimulation.

Although Arabidopsis is an important system for studying root physiology, the localized growth patterns of its roots have not been well defined, particularly during tropic responses. In order to characterize growth rate profiles along the apex of primary roots of Arabidopsis thaliana (L.) Heynh (ecotype Columbia) we applied small charcoal particles to the root surface and analyzed their displacement during growth using an automated video digitizer system with custom software for tracking the markers. When growing vertically, the maximum elongation rate occurred 481 +/- 50 microns back from the extreme tip of the root (tip of root cap), and the elongation zone extended back to 912 +/- 137 microns. The distal elongation zone (DEZ) has previously been described as the apical region of the elongation zone in which the relative elemental growth rate (REGR) is < or = 30% of the peak rate in the central elongation zone. By this definition, our data indicate that the basal limit of the DEZ was located 248 +/- 30 microns from the root tip. However, after gravistimulation, the growth patterns of the root changed. Within the first hour of graviresponse, the basal limit of the DEZ and the position of peak REGR shifted apically on the upper flank of the root. This was due to a combination of increased growth in the DEZ and growth inhibition in the central elongation zone. On the lower flank, the basal limit of the DEZ shifted basipetally as the REGR decreased. These factors set up the gradient of growth rate across the root, which drives curvature.

Automated, eight-cage indirect calorimetry in rats.

We have constructed an automated, eight-cage indirect calorimeter (AIC) for the measurement of energy expenditure in rats. We compared the measurements of resting energy expenditure (REE) in rats during a 30-h fast obtained with the AIC with those obtained with a manual indirect calorimetry (MIC) system. There was both a high degree of correlation between the two techniques during the initial 18 h of the fast (r = 0.90, P < 0.05) and strong intertechnique agreement. REE (AIC) decreased during the final 12 h of the 30-h fast (79.6 +/- 2.7-72.0 +/- 4.4 kcal.kg-0.75.d-1 [mean +/- SD, P < 0.01]). REE (MIC) did not show a significant decrease during this part of the fast (79.7 +/- 2.6 - 75.2 +/- 4.7 kcal.kg-0.75.d-1 [P = NS]). During the final 12 h of the fast agreement between the two systems gradually dissipated and correlation was poor (r = 0.375, P < 0.05). The frequency of animal handling necessitated by MIC may have resulted in a stress-induced increase in metabolic work that would mask the animals' adaptive response to starvation. This investigation demonstrates the advantages of the AIC and calls into question the accuracy of manual methods under long-term starvation conditions.

Resting energy expenditure of patients with gynecologic malignancies.

OBJECTIVE: To evaluate resting energy expenditure compared to predicted energy expenditure in patients with cervical or ovarian carcinoma who require specialized nutritional support. DESIGN: Women with biopsy-proven cervical or ovarian carcinoma referred to the Nutrition Support Service were studied. Resting energy expenditure was measured by indirect calorimetry and compared to predicted energy expenditure (PEE) as determined by the Harris-Benedict equation for females. RESULTS: Sixty one patients were studied. Patients with ovarian cancer (n = 31) had a significantly higher measured resting energy expenditure (% PEE) than patients with cervical cancer (109 +/- 18% vs. 98 +/- 16%, p < 0.02, respectively). This difference in measured resting energy expenditure between groups could not be explained by differences in the extent of disease, nutritional status, body temperature, or nutrient intake between groups. A greater proportion of patients with ovarian cancer were hypermetabolic (> 110% of predicted) in comparison to patients with cervical cancer (55% vs. 13%, p < 0.01, respectively). Measured resting energy expenditure varied between 53% and 157% of predicted for the entire population. CONCLUSION: Ovarian cancer patients are more hypermetabolic than cervical cancer patients. The Harris-Benedict equation for females is a unreliable estimate of caloric expenditure in patients with cervical or ovarian cancer receiving specialized nutritional support.

Long-term enteral access in aspiration-prone patients.

Aspiration pneumonia is a serious complication of enteral feeding. Many critically ill patients are particularly at risk for aspiration. Few studies have rigorously compared various access devices. Risk factors for aspiration and studies examining aspiration associated with enteral feeding devices are reviewed. We recommend a surgical jejunostomy for all patients at high risk for aspiration who require more than 3 weeks of enteral nutrition support.

The button jejunostomy for long-term jejunal feeding: results of a prospective randomized trial.

Low profile, self-retaining feeding conduits ("buttons") inserted percutaneously through a mature gastrostomy stoma are ideal for prepyloric feeding. We tested the efficacy of a surgically inserted button (Button, C.R. Bard, Inc) in the jejunum for long-term postpyloric feeding. Forty-two aspiration risk patients were prospectively randomized to receive a standard No. 14 French red rubber catheter (n = 21, mean age 68 +/- 17 years) or the button (n = 21, mean age 68 +/- 18 years). Common indications for jejunal feeding were aphagia due to obtundation (41%) and esophageal dysmotility (41%). All feeding devices were inserted 20 cm distal to the ligament of Treitz via a serosal tunnel (catheter) or double pursestring (button) technique. No patient required reoperation, and cardiopulmonary failure was the most frequent cause of death, occurring in 11 patients (26%). Goal feedings were obtained in 91% of the catheter patients and 100% of the button patients by postoperative day 4.7 +/- 1.9 and 4.2 +/- 2.2, respectively. At a follow-up of 43 +/- 13 days, 12 (92.3%) of 13 catheter patients and 9 (81.8%) of 11 button patients were receiving goal feedings. Three patients in the catheter group and four patients in the button group had resumed an oral diet. Device-related complications (dislodgment, occlusion, peritubular leak, or bowel obstruction) and total number of patients with complications were significantly lower in the button group (one [5%] vs eight [38%] for device-related complications and one [5%] vs six [29%] for incidence of complications for the button and catheter groups, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Home parenteral nutrition after near total enterectomy.

Six patients with extreme short bowel syndrome (4.2 +/- 4.9 cm of residual small bowel) were provided home parenteral nutrition (HPN) for 14,397 days. The average age at onset of HPN was 38 years (18-64 years). Patients maintained body weight at 97% of ideal (86-112%) with mean serum albumin of 3.7 +/- 0.6 g/dL (normal 3.5-5.8 g/dL), serum transferrin of 341 +/- 104 mg/dL (normal 200-400 mg/dL), and mean serum pre-albumin of 27.5 +/- 12.6 mg/dL (normal 16.6-43 mg/dL). Hospital admission for HPN-related complications was required 10.3 times/patient for a total of 864 hospital days and was catheter related in 71% of episodes. Catheter sepsis occurred once per 436 catheter days and required catheter removal in only 33% of instances. Five patients were able to resume an oral diet, five had returned to work or school, and three were married with family. HPN allowed return to a quality productive life with acceptable morbidity following catastrophic massive bowel resection.

Total quality management: one way to get started.

Continuous QI requires our hospitals to undergo a fundamental change in values, beliefs, and ways to manage. Process improvement changes must start with senior managers, who create the environment for continuous improvement and then enable department managers and employees to improve their processes. Persistent poor quality does not respect organizational boundaries, and HQIP provides an opportunity to manage all the resources necessary to make improvements. As pharmacy managers, we must identify processes under our control that can be continuously improved based on documented customer judgments. We must stop asking employees to work harder in a flawed system and empower them to improve those processes within their control. It may be easy to become frustrated if it seems to take a long time to implement TQM. Remember, transforming our departments and hospitals will not happen overnight. We are embarking on a new style of leadership and management, one that will help pharmacies implement our pharmaceutical care vision.

Laparoscopic-guided jejunostomy.

The proximal jejunum is the preferred site for long-term enteral access in the patient at risk for aspiration. Herein we describe a laparoscopic technique for the creation of a feeding tube jejunostomy. This minimally invasive approach is an alternative for patients requiring chronic postpyloric enteral feeding.